This invention relates to lift wheel chairs that may be used to aid in the transfer of wheelchair-bound individuals to or from a bed, a car seat, a bath, etc. Wheelchairs typically have a frame combined with a seat, a back, enlarged rear wheels, and smaller front wheels. Typical prior art wheelchairs are configured in a collapsible design to allow convenient transportation of the wheelchair, for example, in the trunk of a vehicle. The prior art also includes various elevatable or lift-style wheelchairs as discussed herein.
The present invention is an improved wheelchair that provides a slidable and liftable seat to raise and transfer the wheelchair occupant from the chair to a position for safe and efficient egress to a bed, chair, etc. Unlike the use of a traditional wheelchair, which demands a greater degree of lifting and manipulation by nurses, aids, assistants, or orderlies to move an occupant from the chair, the wheelchair of the present invention allows for the convenient transport through manual or power assisted lifting to position the occupant more safely over or near the destination. By automating portions of the passenger transfer, the amount of lifting required of such assistants, and the risk of injury both to the occupant and the assistant, may be minimized.
U.S. Pat. No. 4,254,791 issued to Antonellis (the '791 patent) discloses an elevatable, side transfer wheelchair that comprises a seat having wheels thereunder and an elevatable base, having tracks thereon, which the wheels may engage. When in use as a wheelchair, the seat with wheels thereunder is locked in place with the wheels in the tracks. The chair is used in combination with a track placed on the seat of an automobile or other vehicle and the chair is operated by first adjusting the elevation of the seat to be coplanar with the tracks on the vehicle seat, unlocking the seat from the stand, and manually sliding the seat from the tracks on the chair base to the tracks on the vehicle. Elevation of the seat may be provided through an electric or pneumatic means.
U.S. Pat. No. 5,884,929 issued to Kincaid (the '929 patent) discloses a wheelchair having a base frame, a seat, and a transfer mechanism to laterally extend the seat from a first position over the frame to a loading or exit position located outwardly from the frame. The seat mechanism rests on a turntable type device to allow rotation of the seat to a convenient position for loading or exiting. The '929 patent does not disclose the vertical shifting, or elevating of the chair or seat, or a mechanism for accomplishing such motion.
U.S. Pat. No. 4,934,723 issued to Dysarz (the '723 patent) by contrast discloses only vertical shifting of the seat. The '723 patent is directed towards an elevating wheelchair that will allow a wheelchair bound individual to obtain a height similar to that of a standing person for conversing face-to-face. The mechanism of the '723 patent includes a leg means that supports the chair and raises the entire chair, including wheels, when the vertical lifting mechanism is activated.
U.S. Pat. No. 4,477,117 issued to Higgs (the '117 patent) discloses a foldable wheelchair having a raisable seat. However, the '117 patent does not disclose a laterally moveable seat or arms or back elements that might be easily folded out of the way to allow an individual to enter or leave the seat. The '117 is specifically directed towards a "safety" foldable wheelchair that would allow a wheelchair bound individual to conduct activities like cooking or other household chores from a safe height rather than at a seated position lower than the working surface.
U.S. Pat. No. 4,669,943 issued to Zamotin (the '943 patent) discloses a wheelchair for transferring an occupant to a motor vehicle. The chair of the '943 patent may be separated from the wheeled frame and left to rest on a vehicle seat. The configuration of the '943 chair includes a base unit having wheels thereon and a vertical side post which engages a side of the seat element. In this manner the configuration is similar to that used in automobile garages to lift or suspend engines, i.e. a side post supports a lifting mechanism and a stabilizing base extends outwardly therefrom.
U.S. Pat. No. 5,096,008 issued to Mankowski (the '008 patent) discloses a stand-up wheelchair. This wheelchair includes a seat that is rotatable and may be lifted from its rear to place the occupant in a standing position. Stability is maintained by locating power means over a central axle and having a second axle located beneath a foot rest. A central wheel is located beneath the interface of the portion that includes the power means and axle and the portion that includes the seat element. In this manner, the footprint of the chair comprises two triangles with a shared apex and the triangle comprised of the apex and the axle that runs beneath the foot rest is rotatable relative to the other triangle.
U.S. Pat. No. 5,209,322 issued to McMahon (the '322 patent) discloses an elevatable seat wheelchair but does not disclose a wheelchair capable of lateral movement to allow convenient entry or unloading of the chair by an occupant.
U.S. Pat. No. 5,060,960 issued to Branscumb (the '960 patent) discloses a combination wheelchair and lifting device wherein a seat is removable and the back rest may be removed or reclined to allow the occupant to recline or to allow access to the occupant's back while seated in the chair. The '960 patent does not disclose a laterally slideable seat.
U.S. Pat. No. 4,278,387 issued to Seguela (the '387 patent) discloses a device for transferring a wheelchair occupant from a vehicle to a wheelchair. The invention discloses a telescoping, laterally moveable seat, but does not disclose a vertically moveable seat. U.S. Pat. No. 5,613,697 issued to Johnson, the '697 patent, discloses merely an elevatable wheelchair. It does not disclose a wheelchair having any laterally moveable seat. U.S. Pat. No. 5,619,762 issued to Mein, the '762 patent discloses an apparatus for aiding a person to stand from a seated position.
Although the prior art discloses chairs adapted to raise a seated occupant, assist an occupant in moving from a seated to a standing position, and even chairs upon which a removable seat may be transferred to an aligned track, there remains, a need for an improved wheelchair that allows for simple lifting to the side of a wheelchair to accommodate the safe transfer of an occupant to a bed, chair, or other destination, from the wheelchair. Accordingly, it is an object of the present invention to provide a wheelchair that provides a power-assisted lifting and transfer function. It is a further object of the present invention to provide such a lifting and transfer function through a slide assembly that may be powered by an extension element to raise and laterally shift a seat from within a wheelchair frame to a position above and beside the frame. It is further still an object of the present invention to provide such a wheelchair wherein stabilizing means are employed to maintain the seat in stable position during occupant transfer and to provide an extendible stabilizer to accommodate the shifting of the center gravity of the occupant/wheelchair system.